WATCH: What is NATO and how is the UK playing a leading role in the alliance?

NATO Secretary General Jens Stoltenberg said the need for Europe and North America to work together was stronger than ever in times of turmoil and unpredictability.

Attending the Munich Security Conference, the Secretary General stressed the importance of fair burden-sharing, noting that all 28 Allies have made clear commitments to increase defence spending.

“For almost 70 years, the partnership between Europe and North America has ensured peace, freedom and prosperity. It enabled us to successfully deter the Soviet Union, and bring the Cold War to an end, and this partnership also enabled the integration of Europe. European leaders have always understood that going it alone is not an option.

And, after two world wars that started in Europe, American leaders know that they have a profound strategic interest in a stable and secure Europe.

The only time we have invoked our collective defence clause, the Article 5, was after an attack on the United States, terrorist attacks on 9/11 in 2001. And this was more than just a gesture. Hundreds of thousands of European and Canadian soldiers have served in Afghanistan in the last 16 years. Around a thousand have paid the ultimate price.